The present invention relates to a receiver for receiving an RF signal transmitting a bit sequence representing a symbol, and to a method for receiving an RF signal transmitting a bit sequence representing a symbol. Some embodiments of the present invention relate to a super regenerative receiver suitable for sub-μA operation.
Standard regenerative receivers comprise a detector with a positive or regenerative feedback from the output to the input. Thereby, the feedback maintains operation of the oscillator on the verge of oscillation. In a super-regenerative receiver, the detector is switched into and out of oscillation by an oscillator operating at a very low frequency rate, called the quench frequency. The quench frequency is lower than the carrier frequency but higher than the frequency of the modulating signal. That is, the quench oscillator allows oscillation to build up in the regenerative circuit and then causes them to die out.
In the absence of an incoming signal, oscillations are initiated by thermal noise, build up to a critical amplitude and die out. An incoming signal larger than the thermal noise advances the build up time. Thus, the maximum oscillation amplitude is reached sooner. A detector will provide indication of an incoming signal based on the advance of the build up period.
Standard super-regenerative receivers are restricted to oversampling at quench frequencies above the data rate of the received signal, in order to accomplish time integration. However, the local oscillator leads to spurious emissions into the environment of the receiver.